AliasAnalysis.h revision 4f1bd9e9963239c119db70070db1d68286b3de7e
14df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner//===- llvm/Analysis/AliasAnalysis.h - Alias Analysis Interface -*- C++ -*-===// 29769ab22265b313171d201b5928688524a01bd87Misha Brukman// 36fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// The LLVM Compiler Infrastructure 46fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// 56fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// This file was developed by the LLVM research group and is distributed under 66fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// the University of Illinois Open Source License. See LICENSE.TXT for details. 79769ab22265b313171d201b5928688524a01bd87Misha Brukman// 86fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell//===----------------------------------------------------------------------===// 94df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// 104df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// This file defines the generic AliasAnalysis interface, which is used as the 114df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// common interface used by all clients of alias analysis information, and 121c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// implemented by all alias analysis implementations. Mod/Ref information is 131c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// also captured by this interface. 144df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// 154df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// Implementations of this interface must implement the various virtual methods, 164df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// which automatically provides functionality for the entire suite of client 174df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// APIs. 184df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner// 191c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// This API represents memory as a (Pointer, Size) pair. The Pointer component 201c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// specifies the base memory address of the region, the Size specifies how large 211c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// of an area is being queried. If Size is 0, two pointers only alias if they 221c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// are exactly equal. If size is greater than zero, but small, the two pointers 231c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// alias if the areas pointed to overlap. If the size is very large (ie, ~0U), 241c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// then the two pointers alias if they may be pointing to components of the same 251c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// memory object. Pointers that point to two completely different objects in 261c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// memory never alias, regardless of the value of the Size component. 271c56b730a6313886076d7b293a126ae5576f5288Chris Lattner// 284df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner//===----------------------------------------------------------------------===// 294df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 304df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner#ifndef LLVM_ANALYSIS_ALIAS_ANALYSIS_H 314df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner#define LLVM_ANALYSIS_ALIAS_ANALYSIS_H 324df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 331c56b730a6313886076d7b293a126ae5576f5288Chris Lattner#include "llvm/Support/CallSite.h" 346df60a9effe4d20a48cfd9d105c0ab3c5dc3e690Reid Spencer#include "llvm/Support/IncludeFile.h" 35d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 36d0fde30ce850b78371fd1386338350591f9ff494Brian Gaekenamespace llvm { 37d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 381c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass LoadInst; 391c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass StoreInst; 4014f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharthclass VAArgInst; 411c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass TargetData; 426df60a9effe4d20a48cfd9d105c0ab3c5dc3e690Reid Spencerclass Pass; 436df60a9effe4d20a48cfd9d105c0ab3c5dc3e690Reid Spencerclass AnalysisUsage; 441c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 451c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerclass AliasAnalysis { 461c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerprotected: 47ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner const TargetData *TD; 48ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner AliasAnalysis *AA; // Previous Alias Analysis to chain to. 49ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 501c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// InitializeAliasAnalysis - Subclasses must call this method to initialize 511c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// the AliasAnalysis interface before any other methods are called. This is 521c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// typically called by the run* methods of these subclasses. This may be 531c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// called multiple times. 541c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 551c56b730a6313886076d7b293a126ae5576f5288Chris Lattner void InitializeAliasAnalysis(Pass *P); 569769ab22265b313171d201b5928688524a01bd87Misha Brukman 571c56b730a6313886076d7b293a126ae5576f5288Chris Lattner // getAnalysisUsage - All alias analysis implementations should invoke this 581c56b730a6313886076d7b293a126ae5576f5288Chris Lattner // directly (using AliasAnalysis::getAnalysisUsage(AU)) to make sure that 591c56b730a6313886076d7b293a126ae5576f5288Chris Lattner // TargetData is required by the pass. 601c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const; 611c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 621c56b730a6313886076d7b293a126ae5576f5288Chris Lattnerpublic: 63ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner AliasAnalysis() : TD(0), AA(0) {} 641c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual ~AliasAnalysis(); // We want to be subclassed 651c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 661c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getTargetData - Every alias analysis implementation depends on the size of 671c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// data items in the current Target. This provides a uniform way to handle 681c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// it. 69dd298c8c6eb036baf35bf5a559c59d2afd2c7944Misha Brukman /// 701c56b730a6313886076d7b293a126ae5576f5288Chris Lattner const TargetData &getTargetData() const { return *TD; } 714df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 721c56b730a6313886076d7b293a126ae5576f5288Chris Lattner //===--------------------------------------------------------------------===// 731c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// Alias Queries... 741c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 754df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 76f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Alias analysis result - Either we know for sure that it does not alias, we 77f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// know for sure it must alias, or we don't know anything: The two pointers 78f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// _might_ alias. This enum is designed so you can do things like: 79f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// if (AA.alias(P1, P2)) { ... } 80f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// to check to see if two pointers might alias. 81f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 821c56b730a6313886076d7b293a126ae5576f5288Chris Lattner enum AliasResult { NoAlias = 0, MayAlias = 1, MustAlias = 2 }; 834df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 84f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// alias - The main low level interface to the alias analysis implementation. 85f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Returns a Result indicating whether the two pointers are aliased to each 86f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// other. This is the interface that must be implemented by specific alias 87f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// analysis implementations. 88f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 891c56b730a6313886076d7b293a126ae5576f5288Chris Lattner virtual AliasResult alias(const Value *V1, unsigned V1Size, 90ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner const Value *V2, unsigned V2Size); 914df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 9262b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// getMustAliases - If there are any pointers known that must alias this 9362b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// pointer, return them now. This allows alias-set based alias analyses to 9462b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// perform a form a value numbering (which is exposed by load-vn). If an 9562b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// alias analysis supports this, it should ADD any must aliased pointers to 9662b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// the specified vector. 9762b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner /// 98ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual void getMustAliases(Value *P, std::vector<Value*> &RetVals); 9962b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner 100762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// pointsToConstantMemory - If the specified pointer is known to point into 101762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// constant global memory, return true. This allows disambiguation of store 102762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// instructions from constant pointers. 103762e8e846f0ad50ffea56216c5ea20db1c95b756Chris Lattner /// 104ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual bool pointsToConstantMemory(const Value *P); 10562b5c167de0ca5883a7ad5eb0900eb0c15ad3707Chris Lattner 106248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner //===--------------------------------------------------------------------===// 107248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// Simple mod/ref information... 108248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 109248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner 110248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefResult - Represent the result of a mod/ref query. Mod and Ref are 111248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// bits which may be or'd together. 112248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 113248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner enum ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 }; 1149769ab22265b313171d201b5928688524a01bd87Misha Brukman 1159769ab22265b313171d201b5928688524a01bd87Misha Brukman 116248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefBehavior - Summary of how a function affects memory in the program. 117248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// Loads from constant globals are not considered memory accesses for this 118248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// interface. Also, functions may freely modify stack space local to their 119248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// invocation without having to report it through these interfaces. 120248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner enum ModRefBehavior { 121248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // DoesNotAccessMemory - This function does not perform any non-local loads 122248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // or stores to memory. 123248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 124248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // This property corresponds to the GCC 'const' attribute. 125248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner DoesNotAccessMemory, 1269769ab22265b313171d201b5928688524a01bd87Misha Brukman 127248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // AccessesArguments - This function accesses function arguments in 128248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // non-volatile and well known ways, but does not access any other memory. 129248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 130248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // Clients may call getArgumentAccesses to get specific information about 131248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // how pointer arguments are used. 132248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner AccessesArguments, 1339769ab22265b313171d201b5928688524a01bd87Misha Brukman 134248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // AccessesArgumentsAndGlobals - This function has accesses function 135248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // arguments and global variables in non-volatile and well-known ways, but 136248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // does not access any other memory. 137248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 138248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // Clients may call getArgumentAccesses to get specific information about 139248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // how pointer arguments and globals are used. 140248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner AccessesArgumentsAndGlobals, 1419769ab22265b313171d201b5928688524a01bd87Misha Brukman 142248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // OnlyReadsMemory - This function does not perform any non-local stores or 143248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // volatile loads, but may read from any memory location. 144248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // 145248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // This property corresponds to the GCC 'pure' attribute. 146248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner OnlyReadsMemory, 1479769ab22265b313171d201b5928688524a01bd87Misha Brukman 148248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // UnknownModRefBehavior - This indicates that the function could not be 149248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner // classified into one of the behaviors above. 150248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner UnknownModRefBehavior 151248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner }; 1529769ab22265b313171d201b5928688524a01bd87Misha Brukman 153248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// PointerAccessInfo - This struct is used to return results for pointers, 154248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// globals, and the return value of a function. 155248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner struct PointerAccessInfo { 156248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// V - The value this record corresponds to. This may be an Argument for 157248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// the function, a GlobalVariable, or null, corresponding to the return 158248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// value for the function. 159248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner Value *V; 1609769ab22265b313171d201b5928688524a01bd87Misha Brukman 161248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ModRefInfo - Whether the pointer is loaded or stored to/from. 162248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 163248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner ModRefResult ModRefInfo; 1649769ab22265b313171d201b5928688524a01bd87Misha Brukman 165248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// AccessType - Specific fine-grained access information for the argument. 166248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// If none of these classifications is general enough, the 167248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// getModRefBehavior method should not return AccessesArguments*. If a 168248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// record is not returned for a particular argument, the argument is never 169248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// dead and never dereferenced. 170248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner enum AccessType { 171248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ScalarAccess - The pointer is dereferenced. 172248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 173248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner ScalarAccess, 1749769ab22265b313171d201b5928688524a01bd87Misha Brukman 175248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ArrayAccess - The pointer is indexed through as an array of elements. 176248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// 177248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner ArrayAccess, 1789769ab22265b313171d201b5928688524a01bd87Misha Brukman 179248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// ElementAccess ?? P->F only? 1809769ab22265b313171d201b5928688524a01bd87Misha Brukman 181248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// CallsThrough - Indirect calls are made through the specified function 182248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// pointer. 183410354fe0c052141dadeca939395743f8dd58e38Chris Lattner CallsThrough 184248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner }; 1859769ab22265b313171d201b5928688524a01bd87Misha Brukman }; 1869769ab22265b313171d201b5928688524a01bd87Misha Brukman 187248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// getModRefBehavior - Return the behavior of the specified function if 188248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// called from the specified call site. The call site may be null in which 189248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner /// case the most generic behavior of this function should be returned. 190248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner virtual ModRefBehavior getModRefBehavior(Function *F, CallSite CS, 191fb752ba02ada9349353b256f81405dd6866c1364Chris Lattner std::vector<PointerAccessInfo> *Info = 0); 1929769ab22265b313171d201b5928688524a01bd87Misha Brukman 1933e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// doesNotAccessMemory - If the specified function is known to never read or 1945cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner /// write memory, return true. If the function only reads from known-constant 19594c420da4a10498c1955d837ed11e66ae3c21dcaChris Lattner /// memory, it is also legal to return true. Functions that unwind the stack 19694c420da4a10498c1955d837ed11e66ae3c21dcaChris Lattner /// are not legal for this predicate. 1973e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 1983e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// Many optimizations (such as CSE and LICM) can be performed on calls to it, 1993e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// without worrying about aliasing properties, and many functions have this 2003e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// property (e.g. 'sin' and 'cos'). 2013e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2023e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property corresponds to the GCC 'const' attribute. 2033e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 204248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner bool doesNotAccessMemory(Function *F) { 205248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner return getModRefBehavior(F, CallSite()) == DoesNotAccessMemory; 206248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner } 2073e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner 2083e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// onlyReadsMemory - If the specified function is known to only read from 20994c420da4a10498c1955d837ed11e66ae3c21dcaChris Lattner /// non-volatile memory (or not access memory at all), return true. Functions 21094c420da4a10498c1955d837ed11e66ae3c21dcaChris Lattner /// that unwind the stack are not legal for this predicate. 2113e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2123e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property allows many common optimizations to be performed in the 2133e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// absence of interfering store instructions, such as CSE of strlen calls. 2143e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 2153e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// This property corresponds to the GCC 'pure' attribute. 2163e295b1b59e47916c8ae5d42eb27a23bd580cabeChris Lattner /// 217248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner bool onlyReadsMemory(Function *F) { 218fb752ba02ada9349353b256f81405dd6866c1364Chris Lattner /// FIXME: If the analysis returns more precise info, we can reduce it to 219fb752ba02ada9349353b256f81405dd6866c1364Chris Lattner /// this. 2208eec644862251e14add0d2707d655fcce91e8f70Chris Lattner ModRefBehavior MRB = getModRefBehavior(F, CallSite()); 2218eec644862251e14add0d2707d655fcce91e8f70Chris Lattner return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory; 222248e8ebeff834db9b78917b1531eeee7035eb113Chris Lattner } 2234df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 2241c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2251c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo - Return information about whether or not an instruction may 2261c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// read or write memory specified by the pointer operand. An instruction 2271c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// that doesn't read or write memory may be trivially LICM'd for example. 2281c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2291c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo (for call sites) - Return whether information about whether 2301c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// a particular call site modifies or reads the memory specified by the 2311c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// pointer. 2321c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 2335cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size); 2341c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 2351c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// getModRefInfo - Return information about whether two call sites may refer 2361c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// to the same set of memory locations. This function returns NoModRef if 237414c36769aff6ec688c49f493122529394357d05Chris Lattner /// the two calls refer to disjoint memory locations, Ref if CS1 reads memory 238414c36769aff6ec688c49f493122529394357d05Chris Lattner /// written by CS2, Mod if CS1 writes to memory read or written by CS2, or 239414c36769aff6ec688c49f493122529394357d05Chris Lattner /// ModRef if CS1 might read or write memory accessed by CS2. 2401c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// 2415cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2); 2421c56b730a6313886076d7b293a126ae5576f5288Chris Lattner 243e40bb915bae2aecdd1578ea356d5e4c8ac31061cChris Lattner /// hasNoModRefInfoForCalls - Return true if the analysis has no mod/ref 244414c36769aff6ec688c49f493122529394357d05Chris Lattner /// information for pairs of function calls (other than "pure" and "const" 245414c36769aff6ec688c49f493122529394357d05Chris Lattner /// functions). This can be used by clients to avoid many pointless queries. 246414c36769aff6ec688c49f493122529394357d05Chris Lattner /// Remember that if you override this and chain to another analysis, you must 247414c36769aff6ec688c49f493122529394357d05Chris Lattner /// make sure that it doesn't have mod/ref info either. 248e40bb915bae2aecdd1578ea356d5e4c8ac31061cChris Lattner /// 249ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual bool hasNoModRefInfoForCalls() const; 250e40bb915bae2aecdd1578ea356d5e4c8ac31061cChris Lattner 2511c56b730a6313886076d7b293a126ae5576f5288Chris Lattner /// Convenience functions... 2521c56b730a6313886076d7b293a126ae5576f5288Chris Lattner ModRefResult getModRefInfo(LoadInst *L, Value *P, unsigned Size); 2535cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(StoreInst *S, Value *P, unsigned Size); 2545cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(CallInst *C, Value *P, unsigned Size) { 2551c56b730a6313886076d7b293a126ae5576f5288Chris Lattner return getModRefInfo(CallSite(C), P, Size); 2561c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 2575cb66e24d42b40d087989199297c369b3f3b2766Chris Lattner ModRefResult getModRefInfo(InvokeInst *I, Value *P, unsigned Size) { 2581c56b730a6313886076d7b293a126ae5576f5288Chris Lattner return getModRefInfo(CallSite(I), P, Size); 2591c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 26014f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth ModRefResult getModRefInfo(VAArgInst* I, Value* P, unsigned Size) { 26114f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth return AliasAnalysis::Mod; 26214f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth } 2631c56b730a6313886076d7b293a126ae5576f5288Chris Lattner ModRefResult getModRefInfo(Instruction *I, Value *P, unsigned Size) { 2641c56b730a6313886076d7b293a126ae5576f5288Chris Lattner switch (I->getOpcode()) { 26514f1703ae33e13dbcadd701603fd4d7a6f7010b9Andrew Lenharth case Instruction::VAArg: return getModRefInfo((VAArgInst*)I, P, Size); 2661c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Load: return getModRefInfo((LoadInst*)I, P, Size); 2671c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Store: return getModRefInfo((StoreInst*)I, P, Size); 2681c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Call: return getModRefInfo((CallInst*)I, P, Size); 2691c56b730a6313886076d7b293a126ae5576f5288Chris Lattner case Instruction::Invoke: return getModRefInfo((InvokeInst*)I, P, Size); 2701c56b730a6313886076d7b293a126ae5576f5288Chris Lattner default: return NoModRef; 2711c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 2721c56b730a6313886076d7b293a126ae5576f5288Chris Lattner } 2734df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 274ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner //===--------------------------------------------------------------------===// 275ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// Higher level methods for querying mod/ref information. 276ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 277ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 278f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// canBasicBlockModify - Return true if it is possible for execution of the 279f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// specified basic block to modify the value pointed to by Ptr. 280f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 2811c56b730a6313886076d7b293a126ae5576f5288Chris Lattner bool canBasicBlockModify(const BasicBlock &BB, const Value *P, unsigned Size); 2824df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 283f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// canInstructionRangeModify - Return true if it is possible for the 284f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// execution of the specified instructions to modify the value pointed to by 285f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// Ptr. The instructions to consider are all of the instructions in the 286f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// range of [I1,I2] INCLUSIVE. I1 and I2 must be in the same basic block. 287f12c2c28bd72091f2d7fff5718265c5ad52e7af8Chris Lattner /// 2884df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2, 2891c56b730a6313886076d7b293a126ae5576f5288Chris Lattner const Value *Ptr, unsigned Size); 290ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 291ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner //===--------------------------------------------------------------------===// 292ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// Methods that clients should call when they transform the program to allow 293ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// alias analyses to update their internal data structures. Note that these 294ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// methods may be called on any instruction, regardless of whether or not 295ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// they have pointer-analysis implications. 296ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 297ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 298ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// deleteValue - This method should be called whenever an LLVM Value is 299ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// deleted from the program, for example when an instruction is found to be 300ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// redundant and is eliminated. 301ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 302ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual void deleteValue(Value *V); 303ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 304ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// copyValue - This method should be used whenever a preexisting value in the 305ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// program is copied or cloned, introducing a new value. Note that analysis 306ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// implementations should tolerate clients that use this method to introduce 307ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// the same value multiple times: if the analysis already knows about a 308ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// value, it should ignore the request. 309ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 310ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner virtual void copyValue(Value *From, Value *To); 311ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner 312ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// replaceWithNewValue - This method is the obvious combination of the two 313ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// above, and it provided as a helper to simplify client code. 314ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner /// 315ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner void replaceWithNewValue(Value *Old, Value *New) { 316ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner copyValue(Old, New); 317ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner deleteValue(Old); 318ab8c565768ff7485f40cbb65e2914f9046e743d4Chris Lattner } 3194df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner}; 3204df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner 3214f1bd9e9963239c119db70070db1d68286b3de7eReid Spencer} // End llvm namespace 3224f1bd9e9963239c119db70070db1d68286b3de7eReid Spencer 323fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// Because of the way .a files work, we must force the BasicAA implementation to 324fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// be pulled in if the AliasAnalysis header is included. Otherwise we run 325fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// the risk of AliasAnalysis being used, but the default implementation not 326fc188b95b81332c12043173c7f517341c6ad27a9Brian Gaeke// being linked into the tool that uses it. 3274f1bd9e9963239c119db70070db1d68286b3de7eReid SpencerFORCE_DEFINING_FILE_TO_BE_LINKED(AliasAnalysis) 3284f1bd9e9963239c119db70070db1d68286b3de7eReid SpencerFORCE_DEFINING_FILE_TO_BE_LINKED(BasicAliasAnalysis) 329d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 3304df22c0100fe27f19e6f4874f24eedd0742b9cf4Chris Lattner#endif 331